1. Field of the Invention
The disclosure relates to a wireless communication system, and particularly to a method for coexistence of different wireless communication systems.
2. Description of Related Art Including Information Disclosed Under 37 CFR 1.97 and 37 CFR 1.98
The current Institute of Electrical and Electronics Engineers (IEEE) 802.16e standard known as WiMax is one kind of wireless metropolitan area network (Wireless-MAN). The IEEE 802.16e standard uses an orthogonal frequency division multiple access (OFDMA) system in its physical layer, has a bandwidth between 1.25 MHz and 20 MHz, and comprises at most 2048 sub-carriers.
The long term evolution (LTE) standard implemented by the third generation partnership project (3GPP) also uses the OFDMA system in its physical layer, and has a bandwidth between 1.4 MHz and 20 MHz. The two aforementioned standards both use the same wireless access system and similar bandwidths. Therefore, an interference issue may occur due to the overlapped channels of these two standards.
FIG. 1 shows a schematic view of a wireless communication system using the IEEE 802.16e standard and the LTE standard. As shown in FIG. 1, the base station BS1 applies the IEEE 802.16e standard, and the base station BS2 applies the LTE standard. The mobile station MS1 is located within the communication range of the base station BS1 but not within the communication range of the base station BS2. The mobile station MS2 is located within the communication range of the base station BS2 but not within the communication range of the base station BS1. Therefore, mobile stations MS1 and MS2 can communicate with base stations BS1 and BS2 respectively without interference between two standards. However, the mobile station MS3 is located within the communication range of the base stations BS1 and BS2, and it may interfere with others or be interfered.
FIG. 2 shows bandwidths of the wireless communication system shown in FIG. 1. As shown in FIG. 2, the base station BS1 uses bandwidth BW1 as its transmission bandwidth, and base station BS2 uses bandwidth BW2 as its transmission bandwidth. In addition, the bandwidth BW1 partially overlaps the bandwidth BW2. Therefore, the mobile station MS3 may interfere with others or be interfered during operation.
With the development of mobile communication systems, the trend of the coexistence of different wireless communication systems is inevitable. Accordingly, there is a need for a method for coexistence of different wireless communication systems; such a method can effectively reduce the interference caused by coexistence of different wireless communication systems. The disclosure provides such a method.